OICC Press Trends in Phytochemical Research 2588-3631 9 4 2025 12 31 Seasonal assessment of the best harvesting months of Bangladeshi Piper betle L. (Piperaceae) leaves: Insights into polyphenols and antioxidant activity using multivariate techniques 10.57647/tpr.2025.0904.22 EN Naim Islam Jahangir Alam https://orcid.org/0009-0000-4156-0424 Manobendra Nath Mohanta https://orcid.org/0009-0003-8908-2232 Mst. Khadiza Khatun Hillol Roy https://orcid.org/0009-0003-7276-3381 Fairuz Islam https://orcid.org/0009-0000-5176-1457 Sunjida Akhter Mst. Fakid Sharmin Sristy https://orcid.org/0009-0003-2024-1055 Md. Mosharef Hossain Bhuiyan Kyong Su Kim Md. Atikul Islam Hajee Mohammad Danesh Science and Technology University https://orcid.org/0000-0002-8162-6464 Journal Article 2025 12 31 This study evaluated monthly and maturity stage variations in polyphenols [total phenol (TP) and total flavonoid (TF)] and antioxidant activity (AA) in Piper betle L. leaves collected between 2021 and 2024. TP and TF were quantified using the Folin-Ciocalteu and aluminum chloride methods, respectively, while AA was measured by DPPH and ABTS assays. TP and TF ranged from 23.56 ± 3.51 to 58.81 ± 26.15 mg GAE/g and 8.93 ± 0.29 to 35.55 ± 0.14 mg QE/g, respectively. IC50 values for DPPH and ABTS varied from 0.45 ± 0.010 to 1.70 ± 0.000 and 0.24 ± 0.001 to 0.87 ± 0.001 (mg AAE/mL), subsequently. The highest TP, TF, and AA were found in March, corresponding to low rainfall (18 mm), moderate temperature (25.35 °C), and humidity (70.5%). Principal component analysis (PCA) and hierarchical cluster analysis (HCA) identified three seasonal clusters. March is recommended as the optimal harvest month to maximize bioactive potential for food, pharmaceutical, and cosmetic applications.